This is a 2 channel graphing meter. Used to check TPS sensors, o2 sensors and MAF's, crank sensor, injector pulse width, and everything else electrical. Shows actual sensor waveform output. Check for dropouts, and proper o2 sensor oscillation. Very useful tool in the right hands. Can be used as a regular volt meter also. Great condition, would like to get $200 shipped. OBO. Comes with case, leads, and paperwork.